Colloid mill



Sept. 19, 1933.

Filed Nov. 8, 1950 ATTORNEYS Patented Sept. 19, 1933 UNITED STATES PATENT OFFICE COLLOID MILL poration of New York Application November 8, 1930. Serial No. 494,251

3 Claims.

The present invention relates to an improvement in colloid mills. One object thereof has been to provide a colloid mill construction in which reduction of particle size and/or dispersion of particles in colloidal suspension is effected in accordance with commonly accepted principles of operation as they are now understood, but with increased efliciency both in the uniformity and quantity of the output as well as in the upkeep and operating characteristics of the mill. In general, colloid machines of known characteristics, utilize closely arranged relatively movable film carrying surfaces such as truncated conical surfaces, cylindrical surfaces, flat faces of discs and irregular surfaces in concentric arrangement. According to my invention, the surfaces between which the film shear takes effect are annular developments of portions of the tractrix or so called Schiele curve, which when embodied in a colloidal mill, present material and beneficial results.

Preferred embodiments of my invention are described in the following specification and illustrated in the accompanying drawing in which Figure 1 is a diametrical section of one form of apparatus; and

Figure 2, a similar view of a modification.

Referring to the drawing, the annular interior surface of a hollow casing 1 presents a radial sectional contour which is approximately a portion of the so-called Schiele curve, the characteristics of which are described at page 155 of Mechanical Engineer's Hand Book, McGraw-Hill Book Company-1916. This interior surface forms part of a stator which cooperates with a rotor 2 also presenting a Schiele curve radial sectional contour and mounted on shaft 3. Suitable adjusting means 4 are provided whereby rotor 2 may be adjusted in respect to the shearing surface of the stator. The shaft 3 is actuated by any suitable means such as a motor, .not shown. Material to be treated is introduced through an inlet pipe 5 and the product is discharged through an outlet 6.

In operation, material to be treated in the mill is fed thereto through the inlet 5 while the rotor 2 is actuated at suitable speed to produce the desired results and with the proper clearance between its film carrying or shearing surface and the shearing surface of the casing 1.

Where the shear surfaces of the rotor and stator or of two rotors are developments of the Schiele curve, the surfaces thereof have the quality when rotated of retaining a surface film of uniform characteristics. That is to say, the tension at all points on the film is uniform and the film is distributed with uniform thickness over said surfaces. Accordingly, when applied to a colloid mill, it will be seen that shear surfaces of the Schiele type insure the uniform treatment of all particles passing between them; whereas, in mills of other types, the conditions referred to are not uniform throughout the whole extent of the shear surfaces and it is believed that the energy applied to effecting colloidal dispersion by means of such surfaces is greatly in excess of the amount actually required. Furthermore, .it is well known that truncated conical surfaces when utilized as contemplated in a colloidal mill are subjected to uneven wear so that any adjustment made at the beginning of an operation may and probably will be disturbed after normal use of the machine for a relatively short time. However, with the shearing surfaces of the Schiele contour, the wear is evenly distributed over the entire surface. A further advantage of this fact is that, although the rotor, for example, may be reduced in its diameter, the stator is correspondingly increased and the relationship of the curved surfaces remains the same, thus permitting by a longitudinal adjustment, the continued use of the parts at normal spaced positions for colloidal work.

Another form of device or colloidal mill employing my invention is illustrated in Figure 2 wherein the colloidal effect is produced by two rotors. For

this purpose, the rotors 7 and 8 are mounted on shafts 9 and 10 respectively extending through a casing 11. Rotor 7 is provided with an interiorly disposed annular surface 12 in opposed relation to a similar interiorly disposed annular surface 13 on the rotor 8. The surfaces 12 and 13 have in radial sectional contour the shape of a portion of the Schiele curve. Shafts 9 and 10 may be actuated by any suitable means, such as a motor, not shown.

In so far as the surface contour of the effective shearing area is concerned, the advantages set forth in respect to the construction shown in Figure 1 are also attained in connection with the construction shown in Figure 2. Of course, where both active factors in the mill are rotors, and where they operate in opposite directions, a greater effective hydraulic shear can be produced between the shearing surfaces than is possible with the type of apparatus shown in Figure 1 at loidal mill construction including the rotor-stator type, the rotor-rotor type with rotors moving in opposite direction and the rotor-rotor type with rotors moving in the same direction but at different speeds.

In connection with the form of device shown in Figure 2 it will be understood that the material to be treated is fed through a centrally disposed or other suitable inlet 14 and, after treatment, is withdrawn through the outlet or discharge opening 15.

I claim as my invention: 1. In a colloid mill, the combination of cooperating members each provided with an annular film carrying surface in opposed relation to the film carrying surface of the other and each of said surfaces approximating a portion of the Schiele curve in its radial sectional contour, and means for effecting differential film shearing movement between saidsurfaces.

2. In a colloid mill, the combination of members having closely adjusted adjacent surfaces relacurve and arranged closely adjacent to the first mentioned surface, means for effecting rotation of the rotatable member, and means for introducing the material to be treated in a film between said working surfaces whereby the particles therein are disintegrated and/or dispersed by reason of the disruptive forces within the film during differential movement between said sur faces.

CHARLES P. TOLMAN. 

